فصلنامه زیست شناسی گیاهی ایران
سال چهارم شماره 1 (پیاپی 11، بهار 1391)

The Region of Yahya Abad is located at the Southern slops of Karkas mountains with about area of 6000 hectare, at 35 kilometres southwest of Natanz. The lowest altitude of this region is 2000 m and the highest altitude is 2720 m. The average annual precipitation is 147.22 mm and mean annual temperature is 15.41 C. The overall plants of the area constituted 190 species belonging to 31 families and 129 genera. A total of 18 genera (62%) and 23 species (12%) belonged to monocotyledons, 111 genera (86%) and 167 species (88%) to dicotyledons. The most families were Asteraceae (36 species), Poaceae (23 species), Fabaceae (19 species), Brassicaceae (18 species), Lamiaceae (17 species), Caryophyllaceae (12 species) and Rubiaceae (5 species). Study of chorology indicated that the most plants were the Irano-Turanian floral elements (71.1%) and Irano-Turan-Euro-Sieberian floral elements (14.4%), among which 35 species were endemic of Iran. In this research, hemicryptophytes (44.7%), therophytes (29%), chamaephytes (18.4%), geophytes (6.3%) and phanerophytes (1.6%) made up the most important life forms, respectively.

Podophyllotoxin (PTOX) is a lignan compound which occurs in a few plant species and has pharmacological significance for its anticancer activities. Linum album, one of endemic species in Iran, has PTOX and other lignans. Chitin and Chitosan are the main compounds of fungal species and as biotic elicitors could be used to improve secondary metabolites. In this study, we investigated the different concentration effects of chitin and chitosan on cell growth, PTOX and lariciresinol production in l. album cell culture. Next, we evaluated the effecr of optimal concentration of chitosan on lignan, phenol, flavonoid, flavonol and lignin content at different times. Treatment of L. album cell cultures with the 100 mg/L chitosan increased the production of PTOX and lariciresinol about two times higher than contol. In addition, Chitosan increased phenol, flavonoid and flavonol. Lignin was increased 2-fold higher than the control in response to chitosan. To study mechanism of chitosan action, phenylalanine ammonio-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) activity were investigated. The activity of PAL and CAD enzymes involved in the first steps of the PTOX biosynthesis was activated by chitosan, reaching a peak within three days after treatment. Chitosan regulated the production of PTOX, lariciresinol and phenylpropanoid compounds by effecting on enzymes activity through PTOX biosynthesis pathway.

Dehydrins are known as late-embryogenesis abundant (LEA) proteins Group II, which are accumulated during low-temperature or water-deficit conditions. They are asumed to play a role in freezing and drought-tolerance in plants. In order to study the impact of dehydrins in response of tolerant and sensitive genotypes to drought, one experiment was carried out in a factorial design based on CRD for a wild ecotype and two barley cultivars in greenhouse. The barley cultivars including Yusef (HV1) and Morocco (HV2) and wild ecotype (HS) were as the first factor and irrigation treatment with three levels consisted of normal (70% of water holding capacity of soil), mild stress (30%) and severe stress (10%) was as the second factor. Normal irrigation was continued in two leaf stage and then discontinued for plants under stress to achieve certain level of stress. The samples were collected from the expanded leaves in vegetative stage for physiological and molecular analysis. Analysis of variance for physiological characteristics showed that the effect of water stress on all traits and differences between genotypes were significant, and HV2 had significantly lower dry mater production and relative water content than the other genotypes. Based on the real time PCR results, among 13 barley dehydrin genes, except for Dhn8 and Dhn13, expression of other genes significantly upregulated under severe drought condition. The expression level of Dhn3, Dhn7, Dhn9 and Dhn10 was increased in the tolerant genotypes, HV1 and HS, whereas the expression level of Dhn1 and the other genes increased only in Yusof and HS, respectively that was indicative of the role of dehydrin genes in drought tolerance. The increase of Dhn12 expression level in wild ecotype through drought condition is reported for the first time in the current study.

During the recent years, unicellular algae have been considered as an important source of unsaturated fatty acids, carotenoids such as beta-carotene and food and drug supplementaries. These algae also play important role as live food in breeding of zooplankton, molluscs and aquatic animals in larval stage. So far many species of different families and generas of unicellular algae have been rightly introduced for aquaculture industry. The family of Scenedesmaceae is known as one of the important microalgae which belongs to Chlorophyceae class. This family is identified with several generas which are all important in aquaculture industry for Artemia, Daphnia and Rotifer breeding. In this research, in order to obtain laboratory demands of unicellular algae, one the most important fresh water sources of west Azerbaijan province, Mahabad dam lake was investigated. This study consisted of morphologic, molecular and nutrition value which resulted in isolation of two species of Scenedesmus obliquus, Kützing 1833 and Desmodesmus cuneatus, Hegewald 2002 of this family. The study of mass and batch culturing potential and also the fatty acid profile of these species revealed efficiency of these species for aquaculture industry. However, in spite of morphologic similarities of the two, the total fatty acids of Desmodesmus cuneatus was found significantly higher than other species (P<0.05).